// GPL Copyright (C) 2000  Paul Makepeace, satur8@hues.org

var r, g, b, its_body;

var t;	// "Let t equal time..."
function psychle_next () {
	t += 1;	// This could be larger to make it seem faster
	        // e.g. 1+10/delay.value -- 10ms is where most browsers seem to max out
	r = 127.5 + 127.5 * Math.sin(t/97);	// These three denominators are (co-)prime,
	g = 127.5 + 127.5 * Math.sin(t/59);	// so shouldn't repeat for a reasonable period:
	b = 127.5 + 127.5 * Math.sin(t/29);	// about four hours with default 100ms delay.
}

// (I can't believe I have to write a dec2hex routine.)
var hex_chars = "0123456789ABCDEF";
function dec2hex(d) {
	return hex_chars.charAt(d/16) + hex_chars.charAt(d%16);
}

// Manipulate calling document's bgColor
function psychle_bgcolor() {
	its_body.bgColor = dec2hex(r) + dec2hex(g) + dec2hex(b);
}

var delay;
// psychle_delay get/set function
function psychle_delay(d) {
	return d ? (delay.value = d) : delay.value;
}

// Entry point. b is the document (body) object whose
// bgColor property we'll poke around with. Shame
// we can't pass the actual bgColor object reference
// itself :-/ (It gets stringified). Mail me if you
// know how to do this!
// d is the initial delay value. We check for a frameset
// and pick up *that* delay object so that it's shared
// (see psychle_2x2.html)
var psychle_on = 0;
function psychle_start(b, d) {
	psychle_on = 1;
	t = 1000 * Math.random();
	its_body = b;
	delay = (top && top.psychle_shared_delay) ? top.psychle_shared_delay : new Object;
	if (d) psychle_delay(d);
	psychle();
}

function psychle_stop(c) {
	psychle_on = 0;
	if (c != null) its_body.bgColor = c;
}

// Main loop.
// count is a limiter just used in development -- change 1 || to 0 || to enable.
var count = 1000;
function psychle() {
	if (!psychle_on) return;
	psychle_next();
	psychle_bgcolor();
	psychle_track();
	if (1 || count-- > 0) setTimeout('psychle()', psychle_delay());
}

// If there is a psychle_track form object in the calling
// document then update its psychle_track_{r,g,b} values
// It would be sexy to have this as a callback so it
// could move around frames.
function psychle_track() {
    if (!its_body.psychle_track) return;
	
	with (its_body.psychle_track) {
		if (!psychle_track_on.checked) return;
		
		psychle_track_r.value = r.toString().substring(0,3);
		psychle_track_g.value = g.toString().substring(0,3);
		psychle_track_b.value = b.toString().substring(0,3);
	}
}